In the prior art, in order to enable a Mobile Station, also referred as User Equipment (UE), to operate normally with Idle mode Signaling Reduction (ISR), Circuit Switched Fallback (CSFB), and interaction through a Short Message Service (SMS) over an SGs interface, a combined Evolved Packet System (EPS)/International Mobile Subscriber Identity (IMSI) attachment capability of the UE has been introduced, where this capability is reported unconditionally in that the capability is made to a Serving General Packet Radio Service (GPRS) Support Node (SGSN) as long as the UE is provided with this capability, that is, the UE needs to report the capability to the SGSN in a Route Area Update (RAU) procedure, and the SGSN deactivates ISR unconditionally upon knowledge of the capability of the UE. The “combined EPS/IMSI attachment capability” as referred to in this context is referred instead to as an “EMM combined procedure capability” in subsequent standardization (where the EMM stands for EPS Mobility Management), and both of them can be interchangeable used in this disclosure.
The following schemes have been proposed to optimize deactivation of ISR:
In a first scheme, deactivation of ISR is not optimized in the prior art;
In a second scheme, deactivation of ISR is optimized so that when the UE is configured to operate with the CSFB or SMSoverSGs feature, the UE reports that it is provided with this capability, and the SGSN deactivates ISR. However a drawback of this scheme lies in that it departs from such a principle that the capability of the UE needs to be reported statically and unconditionally.
In a third scheme, a new indicator is introduced to an RAU Request message to indicate whether the UE registers successfully combined EPS and non-EPS services with an Evolved Universal Mobile Telecommunication System (UMTS) Terrestrial Radio Access Network (E-UTRAN). If they are not registered successfully, then the SGSN can not deactivate ISR for the UE. However a drawback of this scheme lies in that there is additional signaling between the UE and the network and the interface has to be modified, thus resulting in incompatibility.
In a fourth scheme, a new indicator is added to interaction between the SGSN and a Mobility Management Entity (MME) for the MME to indicate to the SGSN whether an SGs interface is set up by the MME for the UE, and the SGSN judges from the indicator whether to deactivate ISR for the UE. A drawback of this scheme lies in there is additional signaling between the MME and the SGSN and the interface has to be modified, thus resulting in incompatibility.
In a fifth scheme, an ISR support bit to indicate a support of ISR between the MME and the SGSN is reused to indicate whether the MME can activate ISR for the UE. When the MME sets up an SGs interface for the UE, this bit is set to “NO”, and the SGSN deactivates ISR in response to the indicating bit. A drawback of this scheme lies in that the ISR support bit is set by modifying what is indicated by the bit to currently refer to the capability of the MME to support ISR but to be independent of the UE.
At present no agreement has been made in the specification about any of the schemes above to optimize deactivation of ISR.
Such a Packet Switched (PS) domain-only (PS-only) feature has been introduced in the discussion of the R11 that is a feature related to a subscription attribute of a subscriber, that is, the UE is provided with a packet service and a short message service (where the short message service is transported over Non Access Stratum (NAS) signaling via the packet domain) over the network via the PS domain according to the subscription data of the subscriber. Since the subscription data of the UE does not limit in any way the capability of the UE used by the subscriber, the UE with a varying capability, e.g., the UE with the combined EPS/IMSI attachment capability is still useable to the subscriber. As per the existing specification, if the UE is provided with this capability, then the UE needs to report an indicator of the capability (i.e., the “combined EPS/IMSI attachment capability”, also referred to as the “EMM combined procedure capability”) unconditionally (i.e., statically), and the SGSN deactivates ISR for the UE upon reception of the indicator of the capability reported by the UE.
However if the subscription data of the subscriber of the UE is PS-only, then it will not be necessary to deactivate ISR because a benefit from the ISR feature, e.g., reduction in unnecessary signaling, energy conservation of the UE, etc., will be lost once ISR is deactivated. There has been absent in the prior art a specific solution to activation and deactivation of ISR according to the PS-only subscription attribute of the subscriber of the UE.